Feast Of The Exaltation Of The Holy Cross - 14 September

Quoted from Learn Religions [1]:

History of the Feast of the Exaltation of the Holy Cross

After the death and resurrection of Christ, both the Jewish and Roman authorities in Jerusalem made efforts to obscure the Holy Sepulchre, Christ's tomb in the garden near the site of His crucifixion. The earth had been mounded up over the site, and pagan temples had been built on top of it. The Cross on which Christ had died had been hidden (tradition said) by the Jewish authorities somewhere in the vicinity.

Saint Helena and the Finding of the True Cross

According to tradition, first mentioned by Saint Cyril of Jerusalem in 348, Saint Helena, nearing the end of her life, decided under divine inspiration to travel to Jerusalem in 326 to excavate the Holy Sepulchre and attempt to locate the True Cross. A Jew by the name of Judas, aware of the tradition concerning the hiding of the Cross, led those excavating the Holy Sepulchre to the spot in which it was hidden.

Three crosses were found on the spot. According to one tradition, the inscription Iesus Nazarenus Rex Iudaeorum ("Jesus of Nazareth, King of the Jews") remained attached to the True Cross. According to a more common tradition, however, the inscription was missing, and Saint Helena and Saint Macarius, the bishop of Jerusalem, assuming that one was the True Cross and the other two belonged to the thieves crucified alongside Christ, devised an experiment to determine which was the True Cross.

In one version of the latter tradition, the three crosses were taken to a woman who was near death; when she touched the True Cross, she was healed. In another, the body of a dead man was brought to the place where the three crosses were found, and laid upon each cross. The True Cross restored the dead man to life....

 

[1] https://www.learnreligions.com/feast-exaltation-of-the-holy-cross-542472, bold and italics original.